Deck 75: Mass Air Flow Sensors

Question 1

A vehicle runs fine when in reverse yet has a rough idle and stalling when put in drive. This could be caused by ________.

A)Incorrect idle speed
B)A cracked air inlet hose
C)A missing spark plug
D)Excessive fuel pressure

Answer 1

A cracked air inlet hose

Question 2

A contaminated sensing wire in a MAF sensor will cause the fuel system to ________ at idle.

A)Shut off
B)Go lean
C)Go rich
D)Be normal

Answer 2

Go rich

Question 3

MAF sensor electrical connectors should be checked for all of these, EXCEPT ________.

A)Over-tight connectors
B)Terminals bent or pushed out of the plastic connector
C)Corrosion
D)Frayed wiring

Answer 3

Over-tight connectors

Question 4

Which of these can be used to measure the frequency (Hz) output of the sensor and compare the reading with specifications?

A)High impedance test light
B)Megohmmeter
C)Logic Probe
D)DMM (digital multimeter)

Question 5

A P0100 DTC is being discussed. Technician A says that an open or short in mass air flow circuit could be the cause. Technician B says that a defective MAF sensor could be the cause. Who is right?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Question 6

Two technicians are diagnosing a poorly running engine with no stored DTCs. When the MAF sensor is unplugged, the engine runs better. Technician A says that this means the MAF is supplying incorrect air flow information to the PCM. Technician B says that this indicates the PCM is defective. Who is right?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Question 7

The MAF sensor on a General Motors 3800 V-6 is being tested for contamination. Technician says that the sensor should show over 100 grams per second on a scan tool display when the accelerator is depressed to WOT (wide open throttle) on a running engine. Technician B says that the output frequency should exceed 7000 Hz when the accelerator pedal is depressed to WOT on a running engine. Who is right?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Question 8

Which airflow sensor has a dampening chamber?

A)A hot wire MAF
B)A hot film MAF
C)A Karman Vortex sensor
D)A vane airflow sensor

Question 9

A P0103 DTC is being discussed. Technician A says that a sensor circuit shorted-to-ground can be the cause. Technician B says that a defective MAF sensor could be the cause. Who is right?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Question 10

What are the two methods of sensing incoming engine air flow?

A)Mass air flow and air intake
B)Speed density and throttle position
C)Speed density and mass air flow
D)EGR and positive crankcase ventilation

Question 11

Technician A says that a MAF sensor actually measures the density and amount of air flowing into the engine. Technician B says a that hot wire MAF sensor uses the electronics in the sensor itself to heat a wire 70°C above the temperature of the air entering the engine. Who is right?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Question 12

Technician A says that a MAF sensor is a high-authority sensor and is responsible for determining the fuel needs of the engine based on the measured amount of air entering the engine. Technician B says that a cold wire MAF sensor uses the electronics in the sensor itself to heat a wire 20°C below the temperature of the air entering the engine. Who is right?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B